1. Field of the Invention
The invention generally relates to fluid treatment system distributor plates and, more particularly, to a distributor plate assembly including a secondary baffle plate positioned beneath the primary distributor plate of such a system.
2. Discussion of the Related Art
Water softeners are widely used for removing calcium and other deposit causing materials from so-called “hard-water.” The typical water softener relies on an ion exchanges process taking place in an ion-exchange resin bed stored in a resin tank or pressure vessel of the water softener. As the water to be processed passes through the resin-filled tank, ions of calcium and other minerals in the water are exchanged with ions found in the resin, e.g., sodium, thereby removing objectionable ions from the water and exchanging them for less objectionable ions from the resin.
The capacity of the resin to exchange ions is finite and is reduced during the ion exchange process. If measures are not taken to regenerate the resin by replacing the undesirable ions with desirable ions, the ion exchange capacity of the resin will become exhausted. Water softeners are typically configured to periodically regenerate the ion exchange resin stored in the resin tank. Regeneration typically involves chemically replacing the objectionable ions such as calcium ions from the resin with less objectionable ions such as sodium ions. The replacement is usually performed by introducing a regenerant solution of sodium chloride or potassium chloride into the resin bed from a brine tank and thereafter flushing the regenerant solution from the bed, i.e., brining. Regeneration of a water softener resin bed is sometimes accomplished in a direction that is co-current with the flow of water to be treated (often referred to as “downflow regeneration” or “service flow”) and is sometimes accomplished in a direction countercurrent to the flow of the water being treated (often referred to as “upflow regeneration” or “backwash flow”). The resin bed is typically backwashed in order to remove trapped particulate matter, and the resin tank can be rinsed to remove objectionable soluble materials. In order to prevent interruption of service, most water softeners are configured to allow bypass of untreated water directly to the service lines during backwash, rinse, and regeneration.
Resin tanks typically employ a distributor plate that allows water to flow through either a filter media bed or an ion exchange bed. Such distributor plates are configured to distribute flow as evenly as possible across the bed to ensure that the entirety of the bed is treated. However, such distributor plates do not operate as efficiently as is desired, particularly in resin tanks employing an upflow brining system. Upflow brining involves forcing water from the brine tank downward through a central riser tube to the bottom of the resin tank and then upward, i.e., upflow, through the distributor plate and the resin bed and out of the top of the tank.
During the brining operation, and particularly the brine draw operation where the brining solution is drawn up through the resin bed, gasses trapped in the fluid are disassociated and form bubbles, which float up through the distributor plate. The bubbles tend to float directly up near the centrally located riser tube and form channels through the resin bed media through which fluid tends to flow, effectively short circuiting the flow of brine past the media.
Further, after the brining process is complete, a slow rinse phase occurs, which is configured to remove excess brine from the resin bed. In the slow rinse phase, raw, untreated water (or, in some systems, treated water) is delivered to the lower end of the resin tank by the riser tube. However, as the rinse water exits bottom of the riser tube, it tends to immediately percolate up through the distributor plate along the riser tube rather than flowing out toward the edge of the tank. This concentrated flow near the riser tube results in the water being concentrated near the center of the tank, leading to insufficient rinsing of media located near the outer edge of the tank.
At least some of these issues are not unique to resin tanks of water conditioning system but, instead, are of a concern in a variety of fluid treatment systems in which a treatment medium is subject to brining.
The need therefore exists to provide a resin tank configured to more uniformly distribute water or other fluid across the entirety of the resin tank during a brining phase and/or a slow rinse phase of an upflow brining process.